A liquid core waveguide fluorescence detector for multicapillary electrophoresis applied to DNA sequencing in a 91-capillary array

A new laser-induced fluorescence (LIF) detector for multicapillary electrop horesis is presented. The detection principle is based on waveguiding of th e emitted fluorescence from the point of illumination to the capillary ends by total internal reflection (TIR) and imaging of the capillary ends. The capillaries themselves thus act as liquid core waveguides (LCWs). At the il lumination point, the capillaries are arranged in a planar array, which all ows clean and efficient illumination with a line-focused laser beam. The ca pillary ends are rearranged into a small, densely packed two-dimensional ar ray, which is imaged end-on with high light collection efficiency and excel lent image quality. Wavelength dispersion is obtained with a single prism. Intercapillary optical crosstalk is less than 0.5%, and rejection of stray light is very efficient. The detector is applied to four-color DNA sequenci ng by gel electrophoresis in a 91-capillary array, with simple fluorescein and rhodamine dyes as fluorophores. Since the imaged two-dimensional array is so compact, the detector has a high potential for very large-scale multi plexing.